I have been using this mod since 2012; offers a plethora of machines to process materials. For me it is the goto tech mod that can be used alongside mesecons and pipeworks, providing automation with reduced effort from the player. My favorite is the windmill, because I can generate energy using air even though the blades don't move.
It is a Debian-like mod; slow, visible updates but high stability.
I love this mod even though it tends to lag many clients.
One of the best features for me is that this mod allows you to double ore output by grinding the ores and then cooking the ground ore into an ingot. This is extremely beneficial to new players who haven't found many resources.
There are several forks for this mod. I personally like the ones that support HV machines and chests that have more features.
I think this mod is a must have on a server that can handle it.